I have a pond nearby. Can I put a loop in it?

Yes, if it’s deep enough and
large enough. A minimum of six feet in depth at its lowest level during the
year is needed for a pond to be considered. The amount of surface area required
depends on the heating and cooling loads of the structure. You should opt
against using water from a spring, pond, lake or river as a source for an open
loop system unless it’s proven to be free of excessive particles and organic
matter. They can clog a heat pump system and make it inoperable in a short
time.